--- title: "Magma V2.18-12 Patch Notes" canonical: "https://docs.magma-maths.org/patchnotes/2.18-12.html" source: "https://docs.magma-maths.org/patchnotes/2.18-12.md" --- # Magma V2.18-12 Patch Notes ## Algebraic Curves - Some problems with residue fields of curves have been fixed. - An incorrect assertion that was causing occasional crashs in [`IsHyperelliptic`](../AlgebraicGeometry/AlgebraicCurves/global-curvepl.md#function-crv-ishyp) and [`CurveQuotient`](../AlgebraicGeometry/AlgebraicCurves/crv_isos.md#function-curvequotient-grpautcrv) has been fixed. ## Algebraic Fields - Residue fields of some places have been optimized. - The inertia degree computation of some prime ideals of relative extensions has been corrected. ## Algebraic Number Fields - A memory issue in `ext<>` has been fixed. - An error message from `meet` of an order with a number field has been corrected. ## Elliptic curves - `TwoDescent` of elliptic curves over `Q` has been improved, fixing extremely bad performance for curves of large conductor with a single two-torsion point. Reported by R. Rathbun. - In [`EightDescent`](../ArithmeticGeometry/EllipticCurvesOverQAndNumberFields/mordell-weil.md#function-eightdescent-crv), some bugs have been fixed which triggered runtime errors in occasional cases. Reported by R. Rathbun. - A bug has been fixed in `EllipticCurveSearch` which caused it to sometimes be very slow for fields of degree 4 or more. Reported by L. Dembele. ## Groups - The construction of BSGS for a matrix group will check if the group is known to be infinite, and will trigger a runtime error if it is. Reported by M. Grassl. - A crash in [`ClassicalMaximals`](../FiniteGroups/AlmostSimpleGroups/properties-lie-groups.md#function-classicalmaximals-monstgelt-rngintelt-rngintelt) when the normalise parameter is set to true has been fixed. Reported by E. O’Brien, fixed by D. Holt. ## Lattices - A crash computing isometry of two lattices with empty sequences of extra forms has been fixed. Reported by M. Kirschmer. ## Modular forms - A much faster version of [`OverconvergentHeckeSeries`](../ModularArithmeticGeometry/ModularForms/overconvergent.md#function-overconvergentheckeseries-rngintelt-rngintelt-rngintelt-rngintelt) has been included. Due to A. Lauder. ## Polynomial Rings - A crash in `ColonIdeal` for ideals over residue class rings has been fixed. Reported by J. Shotton. - `XGCD` now returns all 3 return values when called directly in print mode. Reported by D. Passman. - Evaluation of polynomials at matrices over finite fields has been sped up.